NEWS Glass Expansion Newsletter | October 2013 | Issue 32
Application Spotlight
HOW TO ACH IEVE HIGH ACC URACY WITH DIFFICULT SAMPL ES
In this issue :
• Application Spotlight 1 – 4
• New Products 5 – 6
• Instrument News 7
- From Agilent
- From Spectro
- From Teledyne Technologies
The following report is the result of a collaboration between Glass Expansion and Inorganic Ventures
Introduction
It is very common for ICP labs to encounter samples with a varying degree of total dissolved solids (TDS). However samples with high TDS,
5 to 20%, can often pose many analytical challenges for the ICP analyst. These challenges include short torch lifetime and interrupted analyses
due to clogged nebulizer or injector. Inorganic Ventures is a manufacturer of high-quality analytical inorganic and organic Certified Reference
Material (CRM) standards and custom made CRMs for ICP-OES, ICP-MS, ion chromatography and numerous other testing modalities.
Inorganic Ventures’ certified values are obtained using two independent methods, with traceability to NIST SRMs, and certified uncertainties
are calculated by means of error budgets that include both random and systematic errors.
Inorganic Ventures is accredited by A2LA to ISO Guide 34 and ISO Guide 17025, and registered to ISO 9001. Two of the ISO Guide 34 accreditation
requirements are the assessment of homogeneity and stability of all products covered by this Guide. These assessments are designed and
performed in accordance with ISO Guide 35 and are used to establish the uncertainty components contributed by these properties to the overall
uncertainty of the CRM. The homogeneity assessment should be performed using the same detection principle that is the basis of the measurement
technique by which the CRM is characterized, e.g. a CRM purposed for ICP analysis, should be assessed for homogeneity by ICP. An important
criterion for homogeneity assessment is that the sample remains undiluted. Through dilution, heterogeneity effects may be masked or eliminated,
e.g. dissolved gases or particulates could be re-dissolved by dilution of the sample. As a result of this requirement, Inorganic Ventures analyzes their
reference materials undiluted to assess their homogeneity. This poses a difficult challenge for ICP-OES measurements, as the concentrations of
analytes may range from 100 μg/mL to 10,000 μg/mL and higher concentrations. Under standard ICP-OES operating conditions, the injector and
nebulizer can clog and prematurely shutdown the instrument. Analyzing high TDS samples under standard conditions can also lead to poor precision
and accuracy, increased consumable costs, and down time for instrument maintenance. This report highlights a collaboration with Inorganic Ventures
in which we describe how to optimize the sample introduction system and method parameters of
the ICP to better handle high TDS samples. The performance achieved with a newly introduced
fully ceramic D-Torch for the Spectro Arcos EOP (Axial) ICP-OES is also described.
Figure 1a: Aqueous sample
introduction system, SeaSpray
Choosing the Optimum Nebulizer and Spray Chamber for High TDS
Nebulizer and Twister spray chamber
for Spectro Arcos EOP ICP-OES.
When dealing with any type of new sample you want to be sure to select a nebulizer capable
of handling that particular matrix. A detailed report on nebulizer selection can be found in
our Newsletter (1). When dealing with high TDS samples, Glass Expansion recommends
using the SeaSpray or DuraMist nebulizer for non-HF containing and HF containing samples,
respectively. The SeaSpray nebulizer is a glass concentric nebulizer designed to handle up
to 20% TDS. The DuraMist is also a concentric nebulizer, but features a PEEK body with the
ability to handle up to 5% hydrofluoric acid (HF) and up to 30% TDS(2). Both the SeaSpray
and DuraMist nebulizer offer superior nebulizer efficiency for trace level analysis with the
freedom from clogging due to “salting.” Inorganic Ventures deals with aqueous samples
Figure 1b: HF-resistant sample
and some that contain trace amounts of HF. For this reason our report will focus on the
introduction system, DuraMist
Nebulizer and Tracey TFE spray
performance achieved with both the SeaSpray and DuraMist nebulizer.
chamber for Spectro Arcos
EOP ICP-OES. An HF sample
In this report the Twister spray chamber was used for the non-HF work and the Tracey TFE
introduction kit has been
spray chamber was used for the work with HF. The Twister cyclonic spray chamber includes
configured for the Spectro Arcos
EOP, consisting of a mounting
a baffle which acts as a secondary particle separator, further reducing the mean droplet
bracket, Tracey TFE spray
size entering the torch. This reduces the solvent load in the plasma without compromising
chamber, and PuraFlex transfer
tube (GE P/N 21-809-3689).
detection limits, which is of great importance when dealing with high TDS. For HF
applications, where a glass spray chamber is not suitable, it is necessary to use plastic. The
Tracey TFE and PFA spray chambers are specially treated with Glass Expansion’s proprietary
StediFlow treatment to improve the wettability of the spray chamber’s interior surface. The
StediFlow treatment ensures efficient drainage and provides sensitivity and precision almost
as good as what can be achieved with a glass cyclonic spray chamber. Figures 1a) and 1b),
show photos of the glass and HF-resistant sample introduction systems described above.
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